ABO-Incompatible Kidney Transplantation

Previously, ABO-incompatible kidney transplantation (KTx) was believed to be a “taboo” for immunological reasons. In Japan, the Tokyo Women’s Medical University reported the first successful case of such transplantation, performed on January 19, 1989. Since then, we have been striving to improve the outcome of ABO-incompatible transplantation for a quarter of a century

ABO-incompatible living-donor pediatric kidney transplantation in Japan

The Japanese ABO-Incompatible Transplantation Committee officially collected and analyzed data on pediatric ABO-incompatible living-donor kidney transplantation in July 2012. The age of a child was defined a

SCOPE-RL: A Python Library for Offline Reinforcement Learning and Off-Policy Evaluation

This paper introduces SCOPE-RL, a comprehensive open-source Python software designed for offline reinforcement learning (offline RL), off-policy evaluation (OPE), and selection (OPS). Unlike most existing libraries that focus solely on either policy learning or evaluation, SCOPE-RL seamlessly integrates these two key aspects, facilitating flexible and complete implementations of both offline RL and OPE processes. SCOPE-RL put particular emphasis on its OPE modules, offering a range of OPE estimators and robust evaluation-of-OPE protocols. This approach enables more in-depth and reliable OPE compared to other packages. For instance, SCOPE-RL enhances OPE by estimating the entire reward distribution under a policy rather than its mere point-wise expected value. Additionally, SCOPE-RL provides a more thorough evaluation-of-OPE by presenting the risk-return tradeoff in OPE results, extending beyond mere accuracy evaluations in existing OPE literature. SCOPE-RL is designed with user accessibility in mind. Its user-friendly APIs, comprehensive documentation, and a variety of easy-to-follow examples assist researchers and practitioners in efficiently implementing and experimenting with various offline RL methods and OPE estimators, tailored to their specific problem contexts. The documentation of SCOPE-RL is available at https://scope-rl.readthedocs.io/en/latest/.Comment: preprint, open-source software: https://github.com/hakuhodo-technologies/scope-r

Towards Assessing and Benchmarking Risk-Return Tradeoff of Off-Policy Evaluation

Off-Policy Evaluation (OPE) aims to assess the effectiveness of counterfactual policies using only offline logged data and is often used to identify the top-k promising policies for deployment in online A/B tests. Existing evaluation metrics for OPE estimators primarily focus on the "accuracy" of OPE or that of downstream policy selection, neglecting risk-return tradeoff in the subsequent online policy deployment. To address this issue, we draw inspiration from portfolio evaluation in finance and develop a new metric, called SharpeRatio@k, which measures the risk-return tradeoff of policy portfolios formed by an OPE estimator under varying online evaluation budgets (k). We validate our metric in two example scenarios, demonstrating its ability to effectively distinguish between low-risk and high-risk estimators and to accurately identify the most efficient one. Efficiency of an estimator is characterized by its capability to form the most advantageous policy portfolios, maximizing returns while minimizing risks during online deployment, a nuance that existing metrics typically overlook. To facilitate a quick, accurate, and consistent evaluation of OPE via SharpeRatio@k, we have also integrated this metric into an open-source software, SCOPE-RL (https://github.com/hakuhodo-technologies/scope-rl). Employing SharpeRatio@k and SCOPE-RL, we conduct comprehensive benchmarking experiments on various estimators and RL tasks, focusing on their risk-return tradeoff. These experiments offer several interesting directions and suggestions for future OPE research.Comment: ICLR202

Unbiased Recommender Learning from Missing-Not-At-Random Implicit Feedback

Recommender systems widely use implicit feedback such as click data because of its general availability. Although the presence of clicks signals the users' preference to some extent, the lack of such clicks does not necessarily indicate a negative response from the users, as it is possible that the users were not exposed to the items (positive-unlabeled problem). This leads to a difficulty in predicting the users' preferences from implicit feedback. Previous studies addressed the positive-unlabeled problem by uniformly upweighting the loss for the positive feedback data or estimating the confidence of each data having relevance information via the EM-algorithm. However, these methods failed to address the missing-not-at-random problem in which popular or frequently recommended items are more likely to be clicked than other items even if a user does not have a considerable interest in them. To overcome these limitations, we first define an ideal loss function to be optimized to realize recommendations that maximize the relevance and propose an unbiased estimator for the ideal loss. Subsequently, we analyze the variance of the proposed unbiased estimator and further propose a clipped estimator that includes the unbiased estimator as a special case. We demonstrate that the clipped estimator is expected to improve the performance of the recommender system, by considering the bias-variance trade-off. We conduct semi-synthetic and real-world experiments and demonstrate that the proposed method largely outperforms the baselines. In particular, the proposed method works better for rare items that are less frequently observed in the training data. The findings indicate that the proposed method can better achieve the objective of recommending items with the highest relevance.Comment: accepted at WSDM'2

Macrophage centripetal migration drives spontaneous healing process after spinal cord injury.

Traumatic spinal cord injury (SCI) brings numerous inflammatory cells, including macrophages, from the circulating blood to lesions, but pathophysiological impact resulting from spatiotemporal dynamics of macrophages is unknown. Here, we show that macrophages centripetally migrate toward the lesion epicenter after infiltrating into the wide range of spinal cord, depending on the gradient of chemoattractant C5a. However, macrophages lacking interferon regulatory factor 8 (IRF8) cannot migrate toward the epicenter and remain widely scattered in the injured cord with profound axonal loss and little remyelination, resulting in a poor functional outcome after SCI. Time-lapse imaging and P2X/YRs blockade revealed that macrophage migration via IRF8 was caused by purinergic receptors involved in the C5a-directed migration. Conversely, pharmacological promotion of IRF8 activation facilitated macrophage centripetal movement, thereby improving the SCI recovery. Our findings reveal the importance of macrophage centripetal migration via IRF8, providing a novel therapeutic target for central nervous system injury

Diagnostic accuracy of narrow-band imaging and pit pattern analysis significantly improved for less-experienced endoscopists after an expanded training program

Background: Previous reports assessing diagnostic skill using narrow-band imaging (NBI) and pit pattern analysis for colorectal polyps involved only highly experienced endoscopists. Objective: To evaluate diagnostic skills of less-experienced endoscopists (LEE group) for. differentiation of diminutive colorectal polyps by using NBI and pit pattern analysis with and without magnification after an expanded training program. Design: Prospective study. Patients: This study involved 32 patients with 44 colorectal polyps (27 adenomas and 17 hyperplastic polyps) of 5 mm that were identified and analyzed by using conventional colonoscopy as well as non-magnification and magnification NBI and chromoendoscopy followed by endoscopic removal for histopathological analysis. Intervention: Before a training course, 220 endoscopic images were distributed in randomized order to residents with no prior endoscopy experience (NEE group) and to the LEE group, who had performed colonoscopies for more than 5 years but had never used NBI. The 220 images were also distributed to highly experienced endoscopists (HEE group) who had routinely used NBI for more than 5 years. The images were distributed to the NEE and LEE groups again after a training class. Magnification NBI and chromoendoscopy images were assessed by using the Sano and Kudo classification systems, respectively. Main Outcome Measurements: Diagnostic accuracy and interobserver agreement for each endoscopic modality in each group. Results: Diagnostic accuracy was significantly higher, and kappa (kappa) values improved in the LEE group for NBI with high magnification after expanded training. Diagnostic accuracy and kappa values when using high-magnification NBI were highest among endoscopic techniques for the LEE group after such training and the HEE group (accuracy 90% vs 93%; kappa = 0.79 vs 0.85, respectively). Limitations: Study involved only polyps of <= 5 mm. Conclusion: Using high-magnification NBI increased the differential diagnostic skill of the LEE group after expanded training so that it was equivalent to that of the HEE group

Long-term CMV monitoring and chronic rejection in renal transplant recipients

IntroductionCytomegalovirus (CMV) is well established to be an independent risk factor for graft loss after kidney transplantation (KTx). Monitoring for CMV in the chronic phase is not defined in the current guideline. The effects of CMV infection, including asymptomatic CMV viremia, in the chronic phase are unclear.MethodsWe performed a single-center retrospective study to investigate incidence of CMV infection in the chronic phase, defined as more than 1 year after KTx. We included 205 patients who received KTx between April 2004 and December 2017. The CMV pp65 antigenemia assays to detect CMV viremia were continuously performed every 1–3 months.ResultsThe median duration of the follow-up was 80.6 (13.1–172.1) months. Asymptomatic CMV infection and CMV disease were observed in 30.7% and 2.9% in the chronic phase, respectively. We found that 10–20% of patients had CMV infections in each year after KTx which did not change over 10 years. The history of CMV infection in the early phase (within 1 year after KTx) and chronic rejection were significantly associated with CMV viremia in the chronic phase. CMV viremia in the chronic phase was significantly associated with graft loss.DiscussionThis is the first study to examine the incidence of CMV viremia for 10 years post KTx. Preventing latent CMV infection may decrease chronic rejection and graft loss after KTx

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

Published online 20 June 2016The relationship between purification methods of β-chitin from squid pen and the physicochemical properties of β-chitin nanofibers (NFs) were investigated. Two types of β-chitin were prepared, with β-chitin (a → b) subjected to acid treatment for decalcification and then base treatment for deproteinization, while β-chitin (b → a) was treated in the opposite order. These β-chitins were disintegrated into NFs using wet pulverization. The β-chitin (b → a) NF dispersion has higher transmittance and viscosity than the β-chitin (a → b) NF dispersion. For the first time, we succeeded in obtaining 3D images of the β-chitin NF dispersion in water by using quick-freeze deep-etch replication with high-angle annular dark field scanning transmission electron microscopy. The β-chitin (b → a) NF dispersion has a denser and more uniform 3D network structure than the β-chitin (a → b) NF dispersion. Widths of the β-chitin (a → b) and (b → a) NFs were approximately 8–25 and 3–10 nm, respectively.ArticleINTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES. 91:987-993 (2016)journal articl